Residency · Residency · Neurosurgery

Epidural and Subdural Hematomas: Surgical Indications

Introduction

Epidural hematomas and acute subdural hematomas are two of the most common surgical emergencies in neurotrauma. Rapid recognition and timely surgical intervention are critical determinants of outcome. These extra-axial hemorrhages differ fundamentally in their etiology, clinical course, imaging characteristics, and surgical approach.

Epidural Hematoma

Epidemiology and Etiology

Epidural hematomas occur in 1 to 4 percent of all TBI patients and represent 5 to 15 percent of fatal head injuries. They are most common in young adults aged 20 to 40 years and are uncommon in the elderly because the dura becomes more adherent to the skull with age. The source is arterial in 85 percent of cases, most commonly rupture of the middle meningeal artery following temporal bone fracture. Venous sources account for 15 percent, arising from dural venous sinuses, diploic veins, or the middle meningeal vein. Posterior fossa epidural hematomas represent 5 percent of cases and are often venous, originating from transverse or sigmoid sinus injury.

Clinical Presentation

The classic lucid interval, consisting of initial loss of consciousness followed by transient improvement and then rapid deterioration, is seen in 20 to 50 percent of cases. Ipsilateral pupil dilation from uncal herniation with contralateral hemiparesis indicates progressive mass effect. Progression to coma occurs rapidly if untreated. Posterior fossa EDH presents with headache, vomiting, and rapid deterioration from brainstem compression.

Imaging

CT demonstrates a biconvex or lenticular hyperdense collection that does not cross suture lines because of dural attachments at these locations. The swirl sign, representing mixed density with hypodense areas within hyperdense clot, indicates active bleeding. An associated skull fracture is present in 85 to 95 percent of cases.

Surgical Indications

Brain Trauma Foundation guidelines indicate surgery for EDH greater than 30 milliliters regardless of GCS, thickness greater than 15 millimeters or midline shift greater than 5 millimeters, and neurological deterioration defined as GCS decline of 2 or more points attributable to the EDH. Posterior fossa EDH carries a lower threshold for surgery due to the limited volume of the posterior fossa.

Non-Operative Management

Non-operative management is appropriate for EDH less than 30 milliliters, thickness less than 15 millimeters, midline shift less than 5 millimeters, and GCS above 8 with no focal deficits. This requires serial CT imaging at 6 to 8 hours and then 24 hours with close neurological monitoring in the ICU. A low threshold for surgical intervention applies if any clinical or radiographic progression occurs.

Surgical Technique

The standard approach is a craniotomy, typically temporal or frontotemporal for middle fossa EDH. The clot is evacuated, and the middle meningeal artery is identified and coagulated. Tack-up sutures are placed to obliterate the epidural space and prevent recurrence. An emergent burr hole may be performed as a temporizing measure during transfer if craniotomy is not immediately available.

Acute Subdural Hematoma

Epidemiology and Etiology

Acute SDH is more common than EDH, present in 12 to 30 percent of severe TBI. The source is typically bridging vein rupture from acceleration-deceleration injury that tears veins crossing from the cortex to the dural sinuses, or cortical artery laceration from contusion or penetrating injury. Mortality is higher than EDH at 40 to 60 percent due to greater underlying brain injury. Risk factors include age over 65, anticoagulant or antiplatelet use, cerebral atrophy, and alcoholism.

Clinical Presentation

Patients demonstrate progressive neurological decline, often without a lucid interval. Decreased consciousness, contralateral hemiparesis, and ipsilateral pupil dilation are characteristic. Acute SDH is more commonly associated with significant underlying parenchymal injury including contusions and diffuse axonal injury than EDH. Elderly patients may present insidiously due to greater intracranial reserve from atrophy.

Imaging

CT shows a crescent-shaped or concavo-convex hyperdense collection conforming to the brain surface. Unlike EDH, it crosses suture lines but does not cross the midline because it is limited by the falx. Maximal thickness and midline shift measured at the level of the septum pellucidum are the critical measurements. Associated parenchymal contusions and traumatic subarachnoid hemorrhage are common.

Surgical Indications

BTF guidelines recommend surgery for thickness greater than 10 millimeters or midline shift greater than 5 millimeters regardless of GCS, GCS decline of 2 or more points from the time of injury attributable to the SDH, and ICP above 22 mmHg. All patients with acute SDH and GCS of 8 or below should have ICP monitoring.

Timing of Surgery

Time to surgery is critical. Surgery within 4 hours of injury is associated with improved mortality at 47 percent versus 80 percent. Ultra-early surgical evacuation within 2 hours yields the best outcomes. Every delay compounds secondary injury from mass effect and herniation.

Surgical Technique

A large trauma craniotomy or craniectomy is performed through a generous frontotemporal-parietal bone flap using a question mark incision. Durotomy extends along the entire craniotomy margin, and the clot is evacuated with gentle irrigation. The cortical surface is inspected for active bleeding, and bridging vein stumps are coagulated. If the brain is swollen and does not re-expand after clot evacuation, decompressive craniectomy is performed. A subdural drain is placed, and ICP monitoring is considered.

Comparison of EDH and Acute SDH

Prognostic Factors

EDH Prognosis

Favorable prognostic indicators include rapid surgical intervention, young age, preoperative GCS above 8, and no pupillary abnormalities. Mortality is 5 to 10 percent with prompt surgery but approaches 100 percent if untreated with clinical deterioration. EDH carries the overall best prognosis among traumatic mass lesions.

SDH Prognosis

Unfavorable indicators include age over 65, GCS of 5 or below, bilateral fixed pupils, coagulopathy, and significant midline shift. Mortality ranges from 40 to 60 percent overall and up to 90 percent in patients with GCS 3 and bilateral pupil dilation. Only 20 to 30 percent of survivors achieve functional independence.

Complications

Recurrence is more common with SDH, with reaccumulation requiring reoperation in 5 to 15 percent. Early post-traumatic seizures occur in 10 to 20 percent, and prophylaxis is indicated for 7 days. Cerebral edema with refractory swelling after evacuation may necessitate decompressive craniectomy. Hygroma or chronic SDH develops as a delayed complication of acute SDH evacuation in 10 to 20 percent. Infection including wound infection, empyema, and meningitis is an additional risk.

Clinical Pearls

Epidural hematoma is the most surgically rewarding neurosurgical emergency; excellent outcomes are achievable with rapid evacuation before neurological deterioration occurs. The presence of an acute SDH with minimal thickness but significant midline shift, where the shift exceeds the clot thickness, indicates severe underlying brain swelling and carries a substantially worse prognosis than the SDH alone would suggest. Anticoagulation reversal must occur simultaneously with surgical planning in patients on blood thinners; surgery should not be delayed waiting for complete normalization of coagulation parameters. Posterior fossa EDH is a unique entity requiring lower surgical thresholds due to the small posterior fossa volume and the risk of rapid brainstem compression and obstructive hydrocephalus.

References

1. Bullock MR, Chesnut R, Ghajar J, et al. Surgical management of acute epidural hematomas. Neurosurgery. 2006;58(3 Suppl):S7-15.
2. Bullock MR, Chesnut R, Ghajar J, et al. Surgical management of acute subdural hematomas. Neurosurgery. 2006;58(3 Suppl):S16-24.
3. Seelig JM, Becker DP, Miller JD, et al. Traumatic acute subdural hematoma: major mortality reduction in comatose patients treated within four hours. N Engl J Med. 1981;304(25):1511-1518.
4. Maas AIR, Stocchetti N, Bullock R. Moderate and severe traumatic brain injury in adults. Lancet Neurol. 2008;7(8):728-741.

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